From Release 12 onwards, 3GPP standards has come up with Proximity based Services (ProSe) that enables user equipment's (UEs) to discover and/or to communicate with other UEs directly, without the signal or data packets being routed via network entities. ProSe scenarios are defined for in-coverage, out-of-coverage and partial coverage situations. Communication in partial coverage situation is possible by use of RELAY (ProSe-UE-to-N/W-Relay) services.
For enabling ProSe, new channels and procedures have been defined and system information blocks (SIBS) also have been modified/introduced. Discovery and Communication happens through Side Link (SL) channels. Network has the authorization control (SERVICE AUTHORIZATION) which enables or disables the UEs to discover or communicate or both, to be RELAY, and the like. Prose Direct Discovery is a procedure employed by a ProSe-enabled UE to discover other ProSe-enabled UEs in its vicinity by using LTE direct radio access technology, where UEs need to announce and Monitor certain service related information to discover each other with or without LTE coverage. These procedures are power consuming, which needs to be addressed.
3GPP standards group is currently working on a New WID on Inclusion of WLAN direct discovery technologies as an alternative for Prose direct discovery (from S1-163221). Currently there are various gaps found in WLAN and Prose interworking that need to be addressed for better quality of service to users. The issues are discussed as herein below:
Issue of inclusion of WLAN discovery frame such as, but not limited to, NAN Service Discovery Frame, Wi-Fi P2P Service Discovery Query frame, and the like in PC5 discovery message:
Consider a scenario as described in FIG. 1, wherein FIG. 1 is a schematic diagram 100 illustrating an issue of not sending a WLAN discovery frames in a PC5 discovery message, according to an existing art. FIG. 1 illustrates communication between a user equipment1 (UE1) 102 and a user equipment2 (UE2) 104, wherein there is no provision of sending the WLAN discovery frame over a PC5 link (e.g. LTE prose radio access technology). According to the existing methods, if the UE1 102 discovers the UE2 104 over the PC5 link without EPC support and if both the devices want to communicate over a WLAN radio access technology (using Wi-Fi P2P), then they can't start WLAN communication without performing WLAN discovery. During such instance, the UE1 102 or UE2 104 may have to trigger WLAN direct discovery and then start WLAN communication. Further, if the network is unable to provide service due to congestion and thus wants to re-direct UEs to use WLAN technology for direct discovery or communication, then it is not possible to do directly without performing discovery.
Issue of UE moving out of communication range or signal quality degradation:
Consider a scenario as described in FIG. 3, wherein FIG. 3 is schematic diagram 300 illustrating issue of disconnection of a session on UE moving out of communication range or signal quality degradation, according to an existing art. FIG. 3 illustrates communication between a user equipment1 (UE1) 302 and a user equipment2 (UE2) 304, wherein the two UEs having an ongoing communication session over LTE Prose or WLAN direct access technology, and one of the UEs (e.g. UE2) moves out of the communication range where the radio signal either goes bad either in LTE ProSe or WLAN radio access technology, then the session gets disconnected. As per a prior art, once the connection fails there are no procedure defined to fallback to other D2D (device to device) technology. In other words, there is no fallback mechanism to other 3GPP/non-3GPP access technology defined. The session established by the user will be dropped causing inconvenience to the user.
Issue of UE assisting prose discovery radio access selection (WLAN or LTE Prose):
Consider a scenario as described in FIG. 6, wherein FIG. 6 is a schematic diagram 600 illustrating an issue of UE assisting prose discovery radio access selection, according to an existing art. FIG. 6 illustrates communication between a user equipment1 (UE1) 602 and a user equipment2 (UE2) 604, wherein a prose server 606 can instruct both UE1 602 and UE2 604 to do WLAN direct discovery or communication. For example, when the UE 2 is out of WLAN range, the discovery or communication fails. According to the existing arts, there are no mechanisms defined for the prose server 606 to validate the location of the UEs and accordingly instruct the UEs to start PC5 discovery or communication.
FIG. 8 is schematic diagram 800 illustrating an issue of UE assisted WLAN discovery radio access selection based on UEs' signal condition or performance status, according to another existing art. According to FIG. 8, a Prose server 806 can indicate radio access technology for discovery or communication. There are various scenarios that can occur in existing methods, such as, but not limited to, the WLAN signal strength is below threshold, a UE1 802 or a UE2 804 battery level is low and the UEs may want to use either of the radios (LTE Prose or WLAN), if the UE1 802 or UE2 804 identifies that LTE Prose is providing good signal strength or less network load and want to switch over to the LTE ProSe, or based on geographic location and the like. Then, according to the existing art, there are no methods that UEs can request the Prose server 806 to switch to other access technology or no method/criterion is defined for UE to autonomously switch to other access technology.
Issue of gaps in handling of PC5 Discovery message received over WLAN discovery or communication:
Consider a scenario as described in FIG. 10, wherein FIG. 10 is a schematic diagram 1000 illustrating issue of gaps in handling of PC5 Discovery message received over WLAN discovery or communication, according to an existing art. FIG. 10 illustrates communication between a user equipment1 (UE1) 1002 and a user equipment2 (UE2) 1004, wherein the UE1 1002 may need to perform prose direct discovery procedure for public safety operations and may need to send discovery messages to UE2 1004 or initiate a communication related signaling messages. The UE2 1004, on receiving the WLAN discovery message from the UE1 1002 is not aware of the UE1's 1002 preference for the further discovery/communication operations. The UE2 1004, on receiving the WLAN discovery message from UE1 1002 is not aware whether the UE1 1002 is authorized to use PC5 or not to select PC5 radio access technology for further operations. Also, the Prose server 1006 cannot indicate how UE should initiate further discovery operations on receiving a discovery message over WLAN.
Issue of interworking between devices that support either of the direct discovery or direct communication technologies such as WLAN mode only or Prose mode only supported devices using RELAY UE:
Consider a scenario as described in FIG. 13, wherein FIG. 13 is a schematic diagram 1300 illustrating issue of interworking between WLAN mode and Prose mode only supported devices, according to an existing art. FIG. 13 illustrates communication between a user equipment1 (UE1) 1302 and a user equipment2 (UE2) 1304, wherein the UE1 1302 operating in WLAN mode only and do not supports LTE prose mode. The UE2 is operating in LTE prose mode only do not supports WLAN mode. The UE1 1302 is not be able to do the direct discovery or communication with the UE2 1304. There are no such mechanisms defined for such UEs to interwork. For instance, the UE1 1302 operating in WLAN mode only wants to do restricted discovery to the UE2 1304 which is supporting only LTE Prose, then according to the existing arts, it is not possible.
Issue of Announcement of ETWS or CMAS messages over PC5 or WLAN discovery:
3GPP has standardized a warning message system namely ETWS (Earthquake and Tsunami Warning Service)/CMAS to immediately notify the emergency information to users. As per existing methods, UE's that are not present in the coverage area/region of network will not be able to receive the ETWS or CMAS information.
Issue of power consumption and resource utilization:
ProSe Direct Discovery is a procedure employed by a ProSe-enabled UE to discover other ProSe-enabled UEs in its vicinity by using LTE/WLAN direct radio access technology, Where UE's need to Announce and Monitor certain service related information to discover each other with/without LTE radio access presence. In Prose direct discovery procedure announcing UE will consume more power than a monitoring UE and the power consumption is not centralized between announcing and monitoring UE's.
Prose enabled UE which needs to participate in one to one prose direct communication/which needs to communicate with a relay UE, shall transmit the announce request message periodically until the peer prose UE/Relay UE responds to the announce request. A prose UE which keeps announcing periodically for finding peer UE or relay UE consumes a lot amount of battery power on the UE.
Consider a scenario as described in FIG. 24, wherein FIG. 24 is a schematic diagram 2400 illustrating issue of announcing UE, according to an existing art. A UE1 2402 which is the prose enabled UE and an announce mode, transmits the PC5 announce request message to a UE2 which is a monitor mode) (2404) and a UE 3 which is a monitor mode) 2406 which are the relay UEs or the peer UEs. The UE2 2404 and the UE3 2406 transmit a direct communication request message to the UE1 2402 and no more monitor announcing about the participating in one to one prose direct communication. However, the UE1 2402 still continues to announce the participating in one to one prose direct communication. Therefore, the UE1 2402 transmits the PC5 announce request message to the UE2 2404 and the UE3 2406 periodically.
Issue of Dynamically enable/disable UE to acting as a relay UE:
3GPP has come up with ProSe-UE-to-Network Relay from Rel-13 onwards which enables a remote UE (either out of E-UTRAN coverage or in E-UTRAN coverage) to use N/W services. In the latest releases, 3GPP is talking about UE-to-UE Relays too.
For a UE to be able to act as a ProSe-UE-to-Network Relay or a Remote UE, it should be PROVISIONED and AUTHORIZED by the N/W operator.
Major advantage of UE-to-Network relay is that it helps in extending network coverage. However, if a relay-capable UE is not performing relay (may be intentionally or because of authorization reject from the N/W), remote UEs can't use the N/W services if there's a sudden/temporary overload on the N/W at a certain area, if there is a sudden/temporary outage of N/W at a certain area and if there are temporary or permanent Coverage holes.
Consider a scenario as described in FIG. 26, wherein FIG. 26 is a schematic diagram 2600 illustrating issue of network loss or a coverage hole, according to an existing art. A UE1 (e.g. Relay UE 1) 2602 is not performing relay operation. A UE2 (e.g. Remote UE 2) 2604 and a UE3 (e.g. remote UE 3) 2606 are not able to receive services from the network because of coverage hole, temporary outage of the network or overloading on the network.
Therefore, there is a need of inclusion of the WLAN discovery frame (e.g., NAN service Discovery Frame, WLAN P2P Service discovery query frame etc.) related to WLAN NAN discovery information in a PC5 discovery message. Further, there is a need for session continuity between WLAN and Prose communication. Further, there is a need of UE assisted prose discovery radio access selection in WLAN or LTE ProSe. Further, there is need for a method for receiving the PC5 discovery message over WLAN. Further there is a need for a method of interworking between the devices operating in different radio access technologies. Further there is need for a method of network instructed prose discovery radio access selection for discovery messages received over the WLAN technology. Further there is a need for relaying the emergency warning information to devices not in network coverage. Further there is a need for an announce message from a relay UE will be received by other relay UE during a monitoring phase. Further there is a need for the announcements made by multiple Relay UEs. Further there is a need for enabling a UE to act as a relay UE.
The above-mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.